Two types of ethylene glycol (EG) based nanodiamonds (ND) nanofluids with various diamond phase were prepared. Nanodiamonds were characterized with various techniques like scanning and transmission electron microscopy (SEM, TEM), and energy-dispersive X-ray spectroscopy analysis (EDS). Diamond phases of the materials were 97% and 87% according to manufacturer declaration, and each type of nanofluids were prepared in various mass fraction from 0.01 to 0.1. The paper presents new detailed results on rheological, thermophysical and dielectric properties of these materials. It was presented that those material exhibit viscoelastic, non-Newtonian, thixotropy nature and it depends on purity of NDs. Experimental values of density measurements show that it does not depend on purity of nanodiamonds. On the other hand it was reported that isobaric heat capacity is higher for nanofluids containing ND with higher purity. Results of experiments show also that thermal conductivity enhancement in this material is rather low, and it is slightly higher for more pure NDs. Finally, dielectric profile of these nanofluids was presented, and it show that electrical conductivity of nanosuspension is slightly higher in nanofluids containing NDs with 97% purity. (C) 2018 Elsevier Ltd. All rights reserved.